Integrated apparatus for efficient removal of halogen residues from etched substrates

ABSTRACT

A method and apparatus for removing volatile residues from a substrate are provided. In one embodiment, a method for volatile residues from a substrate includes providing a processing system having a load lock chamber and at least one processing chamber coupled to a transfer chamber, treating a substrate in the processing chamber with a chemistry comprising halogen, and removing volatile residues from the treated substrate in the load lock chamber.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/553,132, filed Oct. 26, 2006 (APPM/10990), which is incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a method and apparatus forfabricating devices on a semiconductor substrate. More specifically, thepresent invention relates to a method and apparatus for removinghalogen-containing residues after plasma etching a layer on asemiconductor substrate.

2. Description of the Related Art

Ultra-large-scale integrated (ULSI) circuits may include more than onemillion electronic devices (e.g., transistors) that are formed on asemiconductor substrate, such as a silicon (Si) substrate, and cooperateto perform various functions within the device. Typically, thetransistors used in the ULSI circuits are complementarymetal-oxide-semiconductor (CMOS) field effect transistors. A CMOStransistor has a gate structure comprising a polysilicon gate electrodeand gate dielectric, and is disposed between a source region and drainregions that are formed in the substrate.

Plasma etching is commonly used in the fabrication of transistors andother electronic devices. During plasma etch processes used to formtransistor structures, one or more layers of a film stack (e.g., layersof silicon, polysilicon, hafnium dioxide (HfO₂), silicon dioxide (SiO₂),metal materials, and the like) are typically exposed to etchantscomprising at least one halogen-containing gas, such as hydrogen bromide(HBr), chlorine (Cl₂), carbon tetrafluoride (CF₄), and the like. Suchprocesses cause a halogen-containing residue to build up on the surfacesof the etched features, etch masks, and elsewhere on the substrate.

When exposed to a non-vacuumed environment (e.g., within factoryinterfaces or substrate storage cassettes) and/or during consecutiveprocessing, gaseous halogens and halogen-based reactants (e.g., bromine(Br₂), chlorine(Cl₂), hydrogen chloride (HCl), and the like) may bereleased from the halogen-containing residues deposited during etching.The released halogens and halogen-based reactants create particlecontamination and cause corrosion of the interior of the processingsystems and factory interfaces, as well as corrosion of exposed portionsof metallic layers on the substrate. Cleaning of the processing systemsand factory interfaces and replacement of the corroded parts is a timeconsuming and expensive procedure.

Several processes have been developed to remove the halogen containingresidues on the etched substrates. For example, the etched substrate maybe transferred into a remote plasma reactor to expose the etchedsubstrate to a gas mixture that converts the halogen-containing residuesto non-corrosive volatile compounds that may be out-gassed and pumpedout of the reactor. However, such process requires a dedicated processchamber along with an additional step, causing increased tool expense,reduced manufacturing productivity and throughput, resulting in highmanufacturing cost.

Therefore, there is a need for an improved method and apparatus forremoving halogen-containing residues from a substrate.

SUMMARY OF THE INVENTION

A method and apparatus for removing volatile residues on an etchedsubstrate are provided. In one embodiment, a method for removingvolatile residues from a substrate includes providing a processingsystem having a load lock chamber and at least one processing chambercoupled to a transfer chamber, treating a substrate in the processingchamber with a chemistry comprising halogen, and removing volatileresidues from the treated substrate in the load lock chamber.

In another embodiment, a method for removing halogen-containing residuesfrom a substrate includes providing a processing system having a loadlock chamber and at least one processing chamber coupled to a transferchamber, treating a substrate in the processing chamber with chemistrycomprising halogen, removing halogen-containing residues from thesubstrate in the load lock chamber, and subsequently cooling thesubstrate in the load lock chamber.

In yet another embodiment, an apparatus suitable for removing halogencontaining residues from a substrate includes at least one etch chamber,a load lock chamber interfaced with a heat module that is adapted toheat a substrate disposed in the load lock chamber, a transfer chamberhaving a robot disposed therein that is adapted to transfer thesubstrate between the etch chamber and the load lock chamber, a remoteplasma source coupled to the load lock chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 depicts a schematic diagram of an exemplary processing apparatusthat includes one embodiment of a load lock chamber suitable forpractice the present invention;

FIG. 2 depicts a sectional view of a load lock chamber utilized in FIG.1;

FIG. 3 depicts a sectional view of one embodiment of a heater module;

FIG. 4 depicts a sectional view of another embodiment of a load lockchamber; and

FIG. 5 depicts a process diagram illustrating a method for removinghalogen-containing residues on a substrate according to one embodimentof the present invention.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

It is to be noted, however, that the appended drawings illustrate onlyexemplary embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to etherequally effective embodiments.

DETAILED DESCRIPTION

The present invention provides a method and apparatus for removinghalogen-containing residues from a substrate etched using an etch antthat includes halogen. In one embodiment, the halogen-containingresidues deposited during substrate etching are removed by a thermaltreatment process performed in a load lock chamber integrated within aprocessing system. The load lock chamber heats the etched substrate andconverts the halogen-containing residues into non-volatile compoundswhich may be pumped out of the load lock chamber. By performing thehalogen-containing residue removal process in the load lock chamberduring the substrate transfer sequence through the load lock chamber,the residue is removed without adversely increasing the overall processcycle time. The invention substantially prevents the environment of theprocessing system and the substrate from contamination and corrosionwhile maintaining high productivity and process throughput.

FIG. 1 is a schematic, top plan view of an exemplary processing system100 that includes one embodiment of a load lock chamber 122 suitable forpracticing the present invention. In one embodiment, the processingsystem 100 may be a CENTURA® integrated processing system, commerciallyavailable from Applied Materials, Inc., located in Santa Clara, Calif.It is contemplated that other processing systems (including those fromother manufacturers) may be adapted to benefit from the invention.

The system 100 includes a vacuum-tight processing platform 104, afactory interface 102, and a system controller 144. The platform 104includes a plurality of processing chambers 110, 112, 132, 128, 120 andat least one load-lock chamber 122 that are coupled to a vacuumsubstrate transfer chamber 136. Two load lock chambers 122 are shown inFIG. 1. The factory interface 102 is coupled to the transfer chamber 136by the load lock chambers 122.

In one embodiment, the factory interface 102 comprises at least onedocking station 108 and at least one factory interface robot 114 tofacilitate transfer of substrates. The docking station 108 is configuredto accept one or more front opening unified pod (FOUP). Two FOUPS 106A-Bare shown in the embodiment of FIG. 1. The factory interface robot 114having a blade 116 disposed on one end of the robot 114 is configured totransfer the substrate from the factory interface 102 to the processingplatform 104 for processing through the load lock chambers 122.Optionally, one or more metrology stations 118 may be connected to aterminal 126 of the factory interface 102 to facilitate measurement ofthe substrate from the FOUPS 106A-B.

Each of the load lock chambers 122 have a first port coupled to thefactory interface 102 and a second port coupled to the transfer chamber136. The load lock chambers 122 are coupled to a pressure control system(not shown) which pumps down and vents the load lock chambers 122 tofacilitate passing the substrate between the vacuum environment of thetransfer chamber 136 and the substantially ambient (e.g., atmospheric)environment of the factory interface 102.

The transfer chamber 136 has a vacuum robot 130 disposed therein. Thevacuum robot 130 has a blade 134 capable of transferring substrates 124between the load lock chambers 122 and the processing chambers 110, 112,132, 128, 120.

In one embodiment, at least one process chambers 110, 112, 132, 128, 120is an etch chamber. For example, the etch chamber may be a DecoupledPlasma Source (DPS) chamber available from Applied Materials, Inc. TheDPS etch chamber uses an inductive source to produce high-density plasmaand comprises a source of radio-frequency (RF) power to bias thesubstrate. Alternatively, at least one of the process chambers 110, 112,132, 128, 120 may be one of a HART™, E-MAX®, DPS®, DPS II, PRODUCER E,or ENABLER® etch chamber also available from Applied Materials, Inc.Other etch chambers, including those from other manufacturers, may beutilized. The etch chambers, for example, chambers 110, 112, 132, 128,120 may use a halogen-containing gas to etch the substrate 124 therein.Examples of halogen-containing gas include hydrogen bromide (HBr),chlorine (Cl₂), carbon tetrafluoride (CF₄), and the like. After etchingthe substrate 124, halogen-containing residues may be left on thesubstrate surface. The halogen containing residues may be removed by athermal treatment process in the load lock chambers 122, as will befurther discussed below.

The system controller 144 is coupled to the processing system 100. Thesystem controller 144 controls the operation of the system 100 using adirect control of the process chambers 110, 112, 132, 128, 120 of thesystem 100 or alternatively, by controlling the computers (orcontrollers) associated with the process chambers 110, 112, 132, 128,120 and the system 100. In operation, the system controller 144 enablesdata collection and feedback from the respective chambers and systemcontroller 144 to optimize performance of the system 100.

The system controller 144 generally includes a central processing unit(CPU) 138, a memory 140, and support circuit 142. The CPU 138 may be oneof any form of a general purpose computer processor that can be used inan industrial setting. The support circuits 142 are conventionallycoupled to the CPU 138 and may comprise cache, clock circuits,input/output subsystems, power supplies, and the like. The softwareroutines, such as a method 500 for removing halogen-containing residuesdescribed below with reference to FIG. 5, when executed by the CPU 138,transform the CPU 138 into a specific purpose computer (controller) 144.The software routines may also be stored and/or executed by a secondcontroller (not shown) that is located remotely from the system 100.

FIG. 2 depicts one embodiment of the load lock chamber 122 utilized toperform a halogen-containing residue removal process. The load lockchamber 122 generally comprises a chamber body 202, a first substrateholder 204, a second substrate holder 206, a temperature controlpedestal 240 and a heater module 270. The chamber body 202 may befabricated from a singular body of material such as aluminum. Thechamber body 202 includes a first side wall 208, a second side wall 210,lateral walls (242 in FIG. 3), a top 214 and a bottom 216 that define achamber volume 218. A window 250 (shown in FIG. 4) typically comprisedof quartz, is disposed in the top 214 of the chamber body 202 and is atleast partially covered by the heater module 270.

The pressure of the chamber volume 218 may be controlled so that theload lock chamber 122 may be evacuated to substantially match theenvironment of the transfer chamber 136 and be vented to substantiallymatch the environment of the factory interface 102. Additionally, thepressure of the chamber volume 218 may be controlled within apredetermined range that facilitates performing the halogen containingresidues removal process, as further described below. The chamber body202 includes one or more vent passages 230 and a pump passage 232. Thevent passage 230 and the pump passage 232 are positioned at oppositeends of the chamber body 202 to induce laminar flow within the chambervolume 218 during venting and evacuation to minimize particulatecontamination. In one embodiment, two vent passages 230 are disposedthrough the top 214 of the chamber body 202, while the pump passage 232is disposed through the bottom 216 of the chamber body 202. The passages230, 232 typically are coupled to a valve 212 to selectively allow flowinto and out of the chamber volume 218. Alternatively, the passages 230,232 may be positioned at opposite ends of one of the chamber walls, oron opposing or adjacent walls. In one embodiment, the vent passage 230is coupled to a high efficiency air filter 236 such as available fromCamfil Farr, Inc., of Riverdale, N.J.

The vent passage 230 may be additionally coupled to a gas source 252through a valve 240 to provide a gas mixture into the chamber volume218. In one embodiment, the vent passage 230 may be configured as a gasdistribution ring wherein the gas mixture may be distributed fromadjacent the walls 210, 208 through an array of holes to optimize theflow uniformity. In another embodiment, the gas mixture may be suppliedto the load lock chamber 202 through a gas distribution plate (notshown) disposed below the heater module 270. The gas distribution platemay be fabricated by a material transmissive to the heat generated fromthe heater module 270 such as not to substantially interfere with theheating of the substrates positioned on the substrate holders 204, 206.Examples of gases that may be supplied from the gas source 252 includenitrogen (N₂), argon (Ar), hydrogen (H₂), alkanes, alkenes, helium (He),oxygen (O₂), ozone (O₃), wafer vapor (H₂O), and the like.

In one embodiment, a remote plasma source (RPS) 248 may be alternativelycoupled to the vent passage 230 to assist in removing thehalogen-containing residues from the substrate surfaces. The remoteplasma source 248 provides plasma formed from the gas mixture providedby the gas source 252 to the load lock chamber 122. In embodiment theremote plasma source (RPS) 248 is present, a diffuser (not shown) may bedisposed at the outlet of the vent passage 230 to facilitate deliverythe generated plasma into the load lock chamber 122.

The pump passage 232 is coupled to a point-of-use pump 236, such asavailable from Alcatel, headquartered in Paris, France. The point-of-usepump 236 has low vibration generation to minimize the disturbance of thesubstrate 124 positioned on the holders 204, 206 within the load lockchamber 122 while promoting pump-down efficiency and time by minimizingthe fluid path between the load lock chamber 122 and pump 236 togenerally less than three feet.

A first loading port 238 is disposed in the first wall 208 of thechamber body 202 to allow the substrate 124 to be transferred betweenthe load lock chamber 122 and the factory interface 102. A first slitvalve 244 selectively seals the first loading port 238 to isolate theload lock chamber 122 from the factory interface 102. A second loadingport 239 is disposed in the second wall 210 of the chamber body 202 toallow the substrate 124 to be transferred between the load lock chamber122 and the transfer chamber 136. A second slit valve 246 which issubstantially similar to the first slit valve 244 selectively seals thesecond loading port 239 to isolate the load lock chamber 122 from thevacuum environment of the transfer chamber 136.

The first substrate holder 204 is concentrically coupled to (i.e.,stacked on top of) the second substrate holder 206 that is disposedabove the chamber bottom 216. The substrate holders 204, 206 aregenerally mounted to a hoop 220 that is coupled to a shaft 282 thatextends through the bottom 216 of the chamber body 202. Typically, eachsubstrate holder 204, 206 is configured to retain one substrate. Theshaft 282 is coupled to a lift mechanism 296 disposed exterior to theload lock chamber 122 that controls the elevation of the substrateholders 204 and 206 within the chamber body 202. A bellows 284 iscoupled between the hoop 220 and the bottom 216 of the chamber body 202and disposed around the shaft 282 to provide a flexible seal between thesecond substrate holder 206 and the bottom 216, thus preventing leakagefrom or into the chamber body 202 and facilitating raising and lowing ofthe substrate holders 204, 206 without compromising the pressure withinthe load lock chamber 122.

The first substrate holder 204 is utilized to hold an unprocessedsubstrate from the factory interface 102 while the second substrateholder 206 is utilized to hold a processed substrate (e.g., an etchedsubstrate) returning from the transfer chamber 136. The flow within theload lock chamber 122 during venting and evacuation is substantiallylaminar due to the position of the vent passage 230 and pump passage 232and is configured to minimize particulate contamination.

FIG. 3 depicts one embodiment of the substrate holders 204, 206 in theload lock chamber 122. The second substrate holder 206 is generally heldabove the bottom 216 of the chamber body 202 by the hoop 220. A firststandoff 308 is disposed between each member 304, 306 to maintain thesecond substrate holder 206 in a spaced-apart relation to the hoop 220.A second standoff 310 is disposed between the first and second substrateholders 204, 206 to maintain a spaced-apart relation therebetween. Thestandoffs 308, 310 allow blades 134, 116 of the transfer and factoryinterface robots 130, 114 to pass therebetween when retrieving anddepositing substrates on the substrate holders 204, 206. Each substrateholder 204, 206 includes a first member 304 and a second member 306.Each holder 204, 206 may have alternatively include a “L-shaped”configuration that incorporates a portion that maintains a spaced-apartrelation between holder 204, 206 and adjacent components of the loadlock chamber 122.

Each member 304, 306 includes a curved inner portion 312 that has a lip314 extending radially inwards therefrom. The curved inner portion 312is generally configured to allow the substrate 124 to pass therebetweenand rest on the lip 314. The curved inner portion 312 captures thesubstrate 124 therebetween, thus preventing the substrate 124 fromfalling off the lip 314.

Referring back to FIG. 2, the temperature control pedestal 240 iscoupled to the bottom 216 of the chamber body 202 by a support 278. Thesupport 278 may be hollow or include passages therethrough to allowfluids, electrical signals, sensor and the like to be coupled to thepedestal 240. Alternatively, the pedestal 240 may be movably coupled tothe chamber body 202 by a second shaft 232 and lift mechanism 296. Inthat embodiment, the support 278 may include a bellows 284.

The temperature control pedestal 240 generally includes a platen 280which is generally fabricated from a thermally conductive material suchas aluminum or stainless steel, but may alternatively be comprised ofother materials, such as ceramic. The platen 280 generally has a heattransfer element 286. The heat transfer element 286 may be a fluidpassage disposed in the platen 280 or disposed in contact with a lowersurface 288 of the platen 280. Alternatively, the heat transfer element286 may be a circulated water jacket, a thermoelectric device, such as aPeltier device, or other structure that may be utilized to control thetemperature of the platen 280.

In one embodiment, the heat transfer element 286 comprises a tube 290disposed in contact with the lower surface 288 of the platen 280. Thetube 290 is coupled to a fluid source 294 that circulates a fluidthrough the tube. The fluid, for example, facility water from the fluidsource 294, may optionally be thermally regulated. The tube 290 may bedisposed in a substantially circular or spiral pattern against the lowersurface 288 of the platen 280. Typically, the tube 290 is brazed to orclamped against the lower surface 288 or adhered using a conductiveadhesive. Optionally, a conductive plate (not shown), such as a copperplate may alternatively be disposed between the tube 290 and platen 280to promote uniformity of heat transfer across the width of the platen280.

The hoop 220 having the substrate holders 204, 206 coupled thereto maybe lowered to a first position where an upper surface 292 of the platen280 is in close proximity or in contact with the substrate supported bythe second substrate holder 206. In the first position, the platen 280may be used to regulate the temperature of the substrate disposed on (orproximate to) the platen 280. For example, a substrate returning fromprocessing may be cooled in the load lock chamber 122 by supporting thesubstrate during the evacuation of the load lock chamber 122 on theupper surface 292 of the platen 280. Thermal energy is transferred fromthe substrate through the platen 280 to the heat transfer element 286,thereby cooling the substrate. After cooling the substrate, thesubstrate holders 204, 206 may be raised towards the top 214 of thechamber body 202 to allow the robots 130, 114 to access to the substrateseated in the second substrate support 206. Optionally, the holders 204,206 may be lowered to a position where the upper surface 292 is incontact or close proximity to the substrate supported by the firstsubstrate holder 204. In this position, the platen 200 may be used tothermally regulate and heat the substrate.

FIG. 4 depicts a sectional view of one embodiment of the heater module270. The heater module 270 is generally disposed on the top 214 of theload lock chamber 122. The heater module 270 may alternatively comprisevarious types of radiant heaters. In one embodiment, the heater module270 includes a housing 402 having one or more lamps 404 disposedtherein. The housing 402 generally includes sides 406 and a top 408 thatdefine an interior 430. The sides 406 are generally coupled to the topof the chamber body 202. An aperture 412 is formed in the top 408 of theheater module 270 to facilitate power connection to the lamp 402. Thelamp 402 is generally coupled to a power source 432 by a ceramic socket414.

A cooling device 416 is coupled to the socket 414 to control thetemperature of the lamps 404, thereby extending the life of the lamps404. In one embodiment, the cooling device 416 is an annular plate 418having good thermal conductivity that is thermally regulated by acirculating fluid. In one embodiment, the annular plate 418 is a copperdisk having a tube 420 brazed to the perimeter of the plate 418. Thefluid is circulated through the tube 420 from a fluid source 434,thereby regulating the temperature of the plate 418. Alternatively, thecooling device 416 may include thermoelectric devices, heat sinks, waterjackets and other devices that limit the temperature rise of the socket414.

The socket 414 is typically biased against the plate 418 to promote heattransfer therebetween. In one embodiment, a shoulder screw 422 isdisposed through the socket 414 and plate 418 and threads into the top408 of the housing 402. To accommodate thermal expansion between thesocket 414 and plate 418, one or more springs 424 may be disposedbetween a head 426 of the shoulder screw 422 and the socket 414. Thespring 424, which may be a coil, flat, belliville or other basisingdevice, maintains contact between the socket 414 and plate 418 over awide range of temperature without damaging the socket 414.

Optionally, a metrology device 428 may be disposed proximate the window250. In one embodiment, the metrology device 428 may be a residual gasanalyzer (RGA). The RGA detects the exhaust gases in the load lockchamber 122 and indicates the ions and species included in the exhaustgas released from the substrate surface. The released exhaust gas ionsand species reflect the amount of halogen-containing residues remainingon the substrate surface, thereby determining an end point for thehalogen-containing residue removal process. In another embodiment, themetrology device 428 may be other types of optical end point detectionsystem that facilitates determination of an end point for thehalogen-containing residue removal process. Alternatively, the metrologydevice 428 may be a substrate type sensor, a substrate orientationsensor, a substrate center sensor, a substrate location sensor, a filmthickness detector, a topography detector or other device utilized todetect attributes of the substrate disposed in the load lock chamber122. Generally, the metrology device 428 is disposed proximate theheater module 270 and positioned to view the substrate through thewindow 250. Alternatively, the metrology device 428 may be disposed inthe heater module 270 or in the chamber volume 218.

Referring back to FIG. 2, in operation, the load lock chamber 122facilitates the transfer of substrates between the ambient atmosphere ofthe factory interface 102 and the vacuum atmosphere of the transferchamber 136. The load lock chamber 122 temporarily houses the substratewhile the atmosphere within the load lock chamber 122 is adjusted tomatch the atmosphere of the transfer chamber 136 or factory interface102 into which the substrate is to be transferred. For example, thefirst slit valve 244 is opened while the load lock chamber 122 is ventedto substantially atmospheric pressure to match the atmosphere of thefactory interface 102. The factory interface robot 120 transfers anunprocessed substrate from one of the FOUP 106A-B to the first substrateholder 204. The substrate subsequently transfers to the processingchambers 110, 112, 132, 128, 120 to perform an etch process. After thehalogen comprising etch process is completed, the pump passage 232 inthe load lock chamber 122 is subsequently opened and the load lockchamber 122 is pumped down to the pressure substantially equal to thepressure of the transfer chamber 136. Once the pressures within the loadlock 122 and transfer chamber 136 are substantially equal, the secondslit valve 246 is opened. The processed substrate is transferred toposition on the second substrate holder 206 by the transfer robot 130 inthe load lock chamber 122. The second slit valve 246 is closed once theblade of the transfer robot 130 is removed.

During halogen-containing residue removal process, the second substrateholder 206 may be raised the processed substrate toward the heatermodule 270 to increase heating efficiency, thereby converting thehalogen-containing residues to non-volatile compounds that may be pumpedout of the load lock chamber 122. During the removal process, one ormore process gases may be supplied into the load lock chamber 122 topromote halogen removal as further discussed below. After thehalogen-containing residues on the processed substrate surface has beenpartially or totally outgassed from the substrate surface, the ventpassage 230 is opened in the load lock chamber 122 to allow the pressurein the load lock chamber 122 to raise to substantially match thepressure in the factory interface 102, thereby facilitating theprocessed substrate being transferred to the FOUPs 106A-B. Whileventing, the pedestal 240 is raised to contact the processed substraterest on the second substrate holder 206. The processed substrate is thuscooled by transferring heat through the pedestal 240 to the fluidcirculating in the tube 290. Once the pressures are matched, the firstslit valve 244 is opened to allow the factory interface robot 114 toaccess the load lock chamber 122 to remove the processed substrate fromthe second substrate holder 206 and return to one of the FOUPs 106A-B.As such, as the substrate cooling process and the load lock chamberventing process is performed simultaneously, the overall process periodand cycle time is reduced and productivity and throughput is increased.A newly unprocessed substrate from the FOUPs 106A-B may be transferredinto the load lock chamber 122 on the first substrate holder 204 as theprocessed substrate removed from the second substrate holder 206 by thefactory interface robot 114 while the slit valve 244 the load lockchamber 122 remains opened.

After completion of the substrate transfer, the first slit valve 244 andvent passage 230 are closed. The pump passage 232 is subsequently openedand the load lock chamber 122 is pumped down to the pressuresubstantially equal to the pressure of the transfer chamber 136. Oncethe pressure of the load lock chamber 122 and the transfer chamber 136are substantially equal, the second slit valve 246 is opened and thetransfer robot 130 then retrieves the newly unprocessed substrate forposition in the first substrate holder 204 for processing in one or moreof the process chambers 110, 112, 132, 128, 120 circumscribing thetransfer chamber 136 to repeatedly and consecutively perform the etchprocess and halogen-containing residue removal process as stated above.After substrate transfer is completed, the second slit valve 246 isclosed to seal the load lock chamber 122 from the transfer chamber 136as stated above.

FIG. 5 depicts a flow diagram of a method 500 for removing ahalogen-containing residue from a substrate in accordance with thepresent invention. The method 500 is configured to perform at theprocessing apparatus 100 as described in FIG. 1. It is contemplated thatthe method 500 may be performed in other suitable processing systems,including those from other manufacturers.

The method 500 begins at step 502 by providing a substrate having alayer disposed thereon which is to be etched in the processing system100. The factory interface robot 114 transfers the substrate to beprocessed from one of the FOUPs 106A-B to the first substrate holder 204in the load lock chamber 122. The substrate may be any substrate ormaterial surface upon which film processing is performed. In oneembodiment, the substrate may have a layer or layers formed thereonutilized to form a structure, such as a gate structure. The substratemay alternatively utilize a mask layer as an etch mask and/or etch stoplayer disposed on the substrate to promote the transfer of the featuresor structures to the substrate. In another embodiment, the substrate mayhave multiple layers, e.g., a film stack, utilized to form differentpatterns and/or features, such as dual damascene structure and the like.The substrate may be a material such as crystalline silicon (e.g.,Si<100> or Si<111>), silicon oxide, strained silicon, silicon germanium,doped or undoped polysilicon, doped or undoped silicon wafers andpatterned or non-patterned wafers silicon on insulator (SOI), carbondoped silicon oxides, silicon nitride, doped silicon, germanium, galliumarsenide, glass, sapphire, metal layers disposed on silicon and thelike. The substrate may have various dimensions, such as 200 mm or 300mm diameter wafers, as well as, rectangular or square panels.

In one embodiment, the substrate transferred to the load lock chamber122 may be preheated to a predetermined temperature by the heater module270 or by the temperature controlled pedestal 240 in the load lockchamber 122. In one embodiment, the substrate may be preheated to atemperature between about 20 degrees Celsius and about 400 degreesCelsius.

At step 504, after the pressure within the load lock chamber 122 and thetransfer chamber 136 are substantially equal, the vacuum robot 130transfers the substrate to one of the processing chambers 110, 112, 132,128, 120. The substrate is etched in one of the processing chamber 110,112, 132, 128, 120 to form desired features and patterns on thesubstrate. In embodiments which the substrate has mask layers disposedon the substrate surface, the etch process etches the mask layerssimultaneously while forming the desired features and patterns.

In one embodiment, the substrate is etched in one of the processingchambers 110, 112, 132, 128, 120 by supplying a gas mixture having atleast a halogen-containing gas. Suitable examples of halogen-containinggas include, but not limited to, hydrogen bromide (HBr), chlorine (Cl₂),carbon tetrafluoride (CF₄), and the like. In an exemplary embodimentsuitable for etching polysilicon, the gas mixture supplied to theprocessing chamber 110, 112, 132, 128, 120 provides a gas mixtureincluding hydrogen bromide (HBr) and chlorine (Cl₂) gas at a flow ratebetween about 20 sccm and about 300 sccm, such as between 20 sccm andabout 60 sccm, for example about 40 sccm. The hydrogen bromide (HBr) andchlorine (Cl₂) gas may have a gas ratio ranging between about 1:0 andabout 1:30, such as about 1:15. An inert gas may be supplied with thegas mixture to the processing chamber 110, 112, 132, 128, 120. Suitableexamples of inert gas may include nitrogen (N₂), argon (Ar), helium (He)and the like. In one embodiment, the inert gas, such as N₂, may besupplied with the gas mixture at a flow rate between about 0 sccm andabout 200 sccm, such as between about 0 sccm and about 40 sccm, forexample about 20 sccm. A reducing gas, such as carbon monoxide (CO) maybe supplied with the gas mixture. The plasma power for the etch processmay be maintained between about 200 Watts and about 3000 Watts, such asabout 500 Watts and about 1500 Watts, for example about 1100 Watts, andthe bias power may be maintained between about 0 Watts and about 300Watts, such as about 0 Watts and about 80 Watts, for example about 20Watts. The process pressure may be controlled at between about 2 mTorrand about 100 mTorr, such as between about 2 mTorr and about 20 mTorr,for example about 4 mTorr, and the substrate temperature may bemaintained at between about 0 degrees Celsius and about 200 degreesCelsius, such as between about 0 degrees Celsius and about 100 degreesCelsius, for example about 45 degrees Celsius.

During etching process, the etched materials may combine with thecomponents of the etchant chemistry, as well as with the components ofthe mask layers, if any, and by-products of the etch process, therebyforming halogen-containing residues. In one embodiment, the materials onthe substrate to be etched may include photoresist layer, hard masklayer, bottom anti-reflective coating (BARC), polysilicon, crystallinesilicon, gate oxide, metal gate, such as Titanium nitride (TiN), andhigh-k materials, such as aluminum oxide (Al₂O₃) and hafnium containingoxide. Suitable examples of hard mask layer include silicon nitride,TEOS, silicon oxide, amorphous carbon, and silicon carbide. Thehalogen-containing residues deposit on the surfaces of the substrate.The halogen-containing residue may release (e.g., outgas) gaseousreactants, such as bromine(Br₂), chlorine(Cl₂), hydrogen chloride (HCl),hydrogen bromine (HBr) and the like, if exposed to atmospheric pressuresand/or water vapor. The release of such reactants may cause corrosionsand particle contamination of the processing apparatus and factoryinterfaces during substrate transfer, such as the vacuum-tightprocessing platform 104 and the factory interface 102 as described inFIG. 1. In embodiments where metallic layers, such as Cu, Al or W, areexposed to the substrate surface, the metallic layer may be corroded bythe released gaseous reactants if they are not removed by the inventiveprocess described below, thereby adversely deteriorating the performanceof devices formed on the substrate.

Halogens may also be present on the surface of substrates that areprocessed in a vacuum environment in a manner other than etching.Therefore, it is contemplated that halogens may be removed from thosesubstrates using the method and apparatus described herein.

At step 506, the processed (e.g., etched) substrate is transferred tothe load lock chamber 122 to remove the halogen-containing residues fromthe substrate generated during step 504 prior to exposure to atmosphericconditions or water vapor in the factory interface or other location.After etch processing, the vacuum robot 130 in the transfer chamber 136transfers the etched substrate from one of the processing chambers 110,112, 132, 128, 120 to the second substrate holder 206 in the load lockchamber 122.

At step 508, a thermal treatment process is performed on the etchedsubstrate to remove the halogen-containing residues on the etchedsubstrate surface. The etched substrate held by the second substrateholder 206 raises the substrate 124 toward the heater module 270,thereby increasing the intensity of heat transfer to the substrate. Theheat from the heater module 270 causes the temperature of the surface ofthe substrate to rise, thereby causing halogen-based reactants disposedon the etched substrate surface to be released and/or outgassed. Theheater module 270 heats the substrate to a temperature between about 20degrees Celsius and about 400 degrees Celsius, such as between about 150degrees Celsius and about 300 degrees Celsius, for example about 250degrees Celsius, at between about 5 seconds and about 30 seconds. Therapid heating of the substrate by heater module 270 allows thehalogen-containing residues on the etched substrate to be removedwithout increasing process cycle time which would be encountered if theresidues were removed in one if the processing chambers. In oneembodiment, the substrate may be heated by the heater module 270 at apredetermined time period until the halogen-containing residues on theetched substrate are removed therefrom. The time or endpoint may bedetermined using the metrology device 428. The etched substrate may beheated at a temperature between about 150 degrees Celsius and about 300degrees Celsius, such as 250 degrees Celsius for between about 10seconds to about 120 seconds, such as between about 30 seconds to about90 seconds.

In one embodiment, a gas mixture may be supplied from the gas source 252to the load lock chamber 122 while heating the etched substrate. Theetched substrate is exposed to and reacts with the gas mixture. The gasmixture converts the outgassed halogen-based reactants intonon-corrosive volatile compounds that are pumped out of the load lockchamber 122. The gas mixture may include an oxygen-containing gas, suchas O₂, O₃, water vapor (H₂O), a hydrogen-containing gas, such as H₂,forming gas, water vapor (H₂O), alkanes, alkenes, and the like, or aninert gas, such as a nitrogen gas (N₂), argon (Ar), helium (He), and thelike. For example, the gas mixture may include oxygen, nitrogen, and ahydrogen-containing gas. In one embodiment, the hydrogen-containing gasis at least one of hydrogen (H₂) and water vapor (H₂O). In embodimentswhich mask layers is present on the substrate, the mask layers may besimultaneously removed with the halogen-containing residues, e.g., themask is stripped of the photoresist in the load lock chamber.

In one embodiment, the gas mixture may be supplied at a flow ratebetween about 100 sccm and about 5000 sccm, such as between about 200sccm and about 1000 sccm, for example about 300 sccm. Alternatively, thegas mixture, for example, may be an O₂ and N₂ gas mixture supplied at agas ratio between about 1:1 and about 20:1, such as between about 10:1.The pressure of the load lock chamber 122 may be maintained at betweenabout 10 mTorr and about 5000 mTorr, such as, between about 100 mTorrand about 1000 mTorr, for example, about 300 mTorr. In embodiments wherethe halogen-containing residues are mostly chlorine-based residuesresulting from use of chlorine-based etching chemistry, the gas mixturemay be oxygen gas (O₂) and/or hydrogen containing gas, such as watervapor (H₂O) and/or H₂. The oxygen gas (O₂) may be supplied at a flowrate at between about 100 sccm and about 5000 sccm and hydrogencontaining gas, such as water vapor (H₂O) and/or H₂ may be supplied at aflow rate at between about 100 sccm and about 3000 sccm. Alternatively,the oxygen gas (O₂) and hydrogen containing gas, such as water vapor(H₂O) and/or H₂, may be supplied at a ratio between about 200:1 andabout 1:1, such as about 150:1 and about 5:1. Alternatively, the gasmixture may be an oxygen gas or a pure hydrogen containing gas, such aswater vapor (H₂O). A residual gas analyzer (RGA), such as the metrologydevice 428 as described in FIG. 4, may be utilized to detect theremaining halogen-containing residues on the etched substrate surface.

In an alternative embodiment, the gas mixture may be provided to theinterior of the load lock chamber 122 through a remote plasma source,such as the remote plasma source 248 in FIG. 2. The remote plasma sourceionizes the gas mixture. The dissociated ions and species promote theconversion of the outgassed halogen-based reactants into non-corrosivevolatile compounds, thereby increasing the removal efficiency of thehalogen-containing residues from the etched substrate surface. In oneembodiment, the remote plasma source may provide a plasma power atbetween about 500 Watts and 6000 Watts. In embodiments where the plasmais present, an inert gas, such as Ar, He or N₂, may be supplied with thegas mixture.

Optionally, a step 509 may be performed wherein the substrate isreturned to one of the processing chambers 110, 112, 132, 128, 120 ofthe system for additional processing prior to removing from the vacuumenvironment. The substrate, after the halogen removal process of step508, will not introduce halogens into the processing chambers duringsubsequent processing, thereby preventing damage to the processingchambers.

At step 510, the temperature control pedestal 240 is raised to contactthe etched substrate supported on the second substrate holder 206 afterthe halogen residue removal step 508 to cool the substrate to a desiredtemperature. The etched substrate is cooled by transferring heat throughthe pedestal 240 to the fluid circulating in the tube 290. In oneembodiment, the etched substrate may be cooled to a temperature rangingbetween about 10 degrees Celsius and about 125 degrees Celsius thatallows the etched substrate to return to the FOUPs 106A-B withoutcausing damage to the FOUPs 106A-B.

While cooling the substrate at step 510, the load lock chamber 122 maybe simultaneously vented in preparation for the subsequent substratetransfer process at step 512 to minimize process cycle time. Once thepressures of the load lock chamber 122 and the factory interface 102 arematched, the first slit valve 244 is opened to allow the factoryinterface robot 114 to access the load lock chamber 122 to remove theetched substrate from the load lock chamber 122 and return to one of theFOUPs 106A-B. A newly unprocessed substrate from the FOUPs 106A-B may betransferred into the load lock chamber 122 on the first substrate holder204 while the etched substrate is removed from the second substrateholder 206, thereby repeatedly and consecutively processing substratesas indicated by the loop 514 depicted in FIG. 5.

Thus, the present invention provides a method and apparatus for removinghalogen and/or halogen-containing residues on a substrate. The methodand apparatus advantageously prevents substrate contamination andcorrosion of exposed portions of metallic films deposited on thesubstrate, along with preventing contamination and corrosion of theprocessing system from by released halogens, thereby enhancingproductivity and process throughput.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. An apparatus for removing halogen-containing residues from asubstrate, comprising: at least one etch chamber; a load lock chamberinterfaced with a heat module that is adapted to heat a substratedisposed in the load lock chamber; a transfer chamber having a robotdisposed therein that is adapted to transfer the substrate between theetch chamber and the load lock chamber; and a remote plasma sourcecoupled to the load lock chamber.
 2. The apparatus of claim 1, whereinthe load lock chamber further comprises: a temperature controlledpedestal disposed in the load lock chamber is configured to cool thesubstrate.
 3. The apparatus of claim 1, wherein the heat module iscapable of heating a substrate disposed in the load lock chamber to atemperature between about 20 degrees Celsius and about 400 degreesCelsius.
 4. The apparatus of claim 1 further comprising: a gas sourcecoupled to the load lock chamber, the gas source containing at least oneof O₂, O₃, water vapor (H₂O), H₂, alkanes, alkenes and nitrogen gas(N₂).
 5. The apparatus of claim 1 further comprising: a gas sourcecoupled to the load lock chamber, the gas source containing at least oneof nitrogen gas (N₂), argon (Ar) and helium (He).
 6. The apparatus ofclaim 1 further comprising: a gas source coupled to the load lockchamber, the gas source configured to provide a gas mixture comprisingO₂ and N₂.
 7. The apparatus of claim 1 further comprising: a powersource arranged to provide a plasma in the load lock chamber.
 8. Theapparatus of claim 1 further comprising: a remote plasma source coupledto the load lock chamber.
 9. The apparatus of claim 8 further comprisinga gas source configured to provide at least one of O₂, O₃, water vapor(H₂O), H₂, alkanes, alkenes, and nitrogen gas (N₂) to the remote plasmasource.
 10. The apparatus of claim 1, wherein the load lock chamberfurther comprises: apparatus for detecting an end point of a volatileresidues removal process performed in the load lock chamber.
 11. Theapparatus of claim 1 further comprising: a gas source coupled to theetch chamber, the gas source configured to provide at least one ofhydrogen bromide (HBr), chlorine (Cl₂), and carbon tetrafluoride (CF₄).